To go one step further, that option comes with the 2-rail wheels that don't work so hot on Ross switches. You can buy the hi-rail wheel sets for another $60 which brings the total of $560 (plus tax) for a very cool, wide-curve running, fixed pilot beauty. I'm thinking seriously of doing this with the new SD70ACe with the new Cat paint scheme.
I attempted this 6 years ago when the SD70ACe in the Southern Pacific heritage scheme. It came through the 2-rail wheels and I was going to buy the conversion set, BUT... The engine had some quality problems, mainly the PE running boards buckled. If you pressed on the bulge, it would just pop up somewhere else. My LHS sent it back to MTH. It came back with the bulges AND broken sun visors. I was not happy, returned the engine to my LHS and traded it for the DAP N-S, A-B-B-A F7 trainset and have enjoyed it since.
I would like to take the chance and do it again. I don't like swinging pilots and with O-88 and O-96 throughout, I don't need them.